Heat the oven: Preheat to 425°F (220°C).
Line a baking sheet with parchment for easy cleanup.
Prep the sweet potatoes: Scrub them clean, pat dry, and poke each 4–5 times with a fork. Rub with olive oil and a pinch of salt. Place on the baking sheet.
Bake until tender: Roast for 40–55 minutes, depending on size, until a knife slides through easily and the skins look slightly wrinkled.
Cook the taco filling: While the potatoes bake, warm 1 tablespoon olive oil in a skillet over medium heat.
Add the onion and sauté 3–4 minutes until softened. Add the garlic and cook 30 seconds.
Brown the protein: Add ground meat and cook, breaking it up, until no longer pink. If using beans or lentils, warm them in the skillet with the onions and garlic for 2–3 minutes.
Season it: Stir in chili powder, cumin, smoked paprika, garlic powder, onion powder, oregano, salt, pepper, and optional cayenne.
Toast the spices for 30 seconds to bloom the flavors.
Make it saucy: Add tomato paste and water (or broth). Stir and simmer 2–4 minutes until slightly thickened and glossy. Taste and adjust salt or spice.
Fluff the potatoes: When the sweet potatoes are done, let them cool a few minutes.
Slice them lengthwise, gently push the ends toward the center, and fluff the flesh with a fork.
Cheese layer: Sprinkle a little cheese inside each sweet potato so it melts into the hot flesh.
Stuff and top: Spoon the taco filling into each potato. Add more cheese if you like, then top with lettuce, avocado, salsa, cilantro, and a dollop of sour cream or Greek yogurt. Finish with a squeeze of lime.
Serve: Plate with extra lime wedges and your favorite hot sauce.
Add tortilla chips on the side for crunch if you want.